1. Field of the Invention
The present invention relates to an air conditioner, and particularly, to a method for controlling an operation of an air conditioner having an inverter compressor and a regular velocity compressor.
2. Description of the Background Art
In general, an air conditioner controls a temperature, humidity, air current distribution of a certain space to be proper to a human activity and is an apparatus for cooling a room by using a principle of evaporation heat that heat is taken from the ambient when a refrigerant compressed at a high temperature and high pressure through various kinds of compressor is evaporated. Here, liquid that is easily evaporated even at a low temperature is used as the refrigerant, and generally, Freon gas is used.
FIG. 1 is a block diagram showing a schematic structure of an air conditioner in accordance with the conventional art.
As shown therein, an air conditioner in accordance with the conventional art includes: a control unit 10 measuring a room temperature and outputting a control signal for controlling cooling capacity based on the measured temperature and a preset temperature; a compressor unit 20 compressing a refrigerant based on the control signal; a condenser 30 condensing the refrigerant compressed by the compressor unit 20; a expansion valve 40 for expanding the refrigerant condensed by the condenser 30; and an evaporator 50 evaporating the refrigerant expanded by the expansion valve 40.
An operation principle of the air conditioner according to the conventional art constructed as above will now be described in detail.
First, the control unit 10 measures a room temperature and outputs a control signal for controlling a cooling capacity based on the measured room temperature and a temperature preset by a user.
In the compressor unit 20, an inverter compressor, a first compressor 21 is used as a small capacity compressor, and a regular velocity compressor, a second compressor 22 is used as a large capacity compressor. The first and second compressors 21 and 22 are selectively driven according to the control signal, thereby compressing the refrigerant at a high temperature and high pressure. Namely, the compressor unit 20 is driven in a mode that only the first compressor is driven, a mode that only the second compressor is driven, or a mode that both first and second compressors are driven, to thereby vary a compressing capacity of a refrigerant required for cooling.
Here, a control range of a cooling capacity is varied depending on kinds of first and second compressors, and the first and second compressors are largely divided to the regular velocity compressor and the inverter compressor. In case of the regular velocity compressor, since the compressor has a constant operation speed, a room temperature is controlled by turning on/off the compressor. However, in case of the inverter compressor, since the compressor controls its operation speed, a room temperature can be relatively precisely controlled by controlling its operation frequency
For example, assuming that the first compressor 21 is a regular velocity compressor having a compressing capacity of 30, and the second compressor 22 is a regular velocity compressor having a compressing capacity of 40, an air conditioner to which the first and second compressors are applied can control a room temperature with a compressing capacity of 30, 40 or 70.
However, assuming that the first compressor 21 is an inverter compressor having a compressing capacity of 30, and the second compressor 22 is a regular velocity compressor having a compressing capacity of 40, the air conditioner to which the first and second compressors are applied can relatively precisely controls a room temperature with a compressing capacity of 10, 20, 30, 40, 50 60 or 70. Here, in general, the inverter compressor controls the compressing capacity by the unit of 10.
The condenser 30 condenses a refrigerant compressed at a high temperature and high pressure by the compressor unit 20, and the expansion valve 40 expands the condensed refrigerant. In addition, the evaporator 50 evaporates the expanded refrigerant and takes heat from around the evaporator 50, so that heat exchange which drops a temperature of air coming in contact with a surface of the evaporator 50 is performed.
In the air conditioner in accordance with the conventional art, a regular velocity compressor and an inverter compressor are used as compressors used to control a cooling capacity, so that the cooling capacity can be precisely controlled according to a cooling load. A change of a room temperature according to the air conditioner driven in such a manner will now be described with reference to FIG. 2.
FIG. 2 is a graph showing a change of a room temperature due to a method for controlling an operation of an air conditioner in accordance with the conventional art.
As shown therein, when a room temperature reaches an upper limit temperature or a lower limit temperature of a desired temperature set by a user, the regular velocity compressor is turned on/off or an operation frequency of the inverter compressor is controlled, so that the room temperature is controlled within a certain range.
However, the air conditioner in accordance with the conventional art is disadvantageous in that when a desired temperature set by a user is maintained for a long time, a user feels cold and thus cannot feel pleasantness at the desired temperature set by himself/herself.